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/******************************************************************************************
*******************************************************************************************
Chapter 3 Stack and Queue

Write a program to sort a stack in ascending order.
You should not make any assumptions about how the stack is implemented.
The following are the only functions that should be used to write this program: push | pop | peek | isEmpty.

peek: return the top value of stack without removing it.

We use two stacks for ordering the elements. The main stack contains the elements in a sorted fashion. 
The auxulary stack is used to sort the elements of the main stack if required. 
memory  O(n)
time       O(n^2)

Questions:

how can we write this function with the memory of O(1)?
how about a time of O(n)? is that possible?


By: Hamed Kiani (Sep. 14, 2015)
******************************************************************************************
******************************************************************************************/

#include "stdafx.h"
#include <iostream>
using namespace std;

class sortedStack{

private:
        int *_mainStack;     // main ordered stack
        int *_auxStack;              // auxulary stack for ordering
        int _size;                       // the max size of stack for overflow checking
        int _top;                        // index of the top element of main stack
        int _aux_top;            // index of the top element of aux stack

public:
        sortedStack(int n);      // constructor
        ~sortedStack();             // destructor
        bool isEmpty();           // is the stack empty?
        bool isFull();            // is the stack full?
        void push(int data);       // ordered push
//         void ordered_push(int data);
        void pop();                       // normal pop operation
        int peek();                       // peek function   
        void print();             // print the main stack
};

////////////////////////////////////////////////////////////
sortedStack::sortedStack(int n)
{
        _size = n;
        _top = -1;
        _aux_top = -1;
        // initializaing the main and aux stacks
        _mainStack = (int*) malloc(sizeof(int) * _size);
        _auxStack  = (int*) malloc(sizeof(int) * _size);
}

////////////////////////////////////////////////////////////
sortedStack::~sortedStack()
{
        free(_mainStack);
        free(_auxStack);        
}

////////////////////////////////////////////////////////////
bool sortedStack::isEmpty()
{
        return (_top == -1);
}

////////////////////////////////////////////////////////////
bool sortedStack::isFull()
{
        return (_top == _size-1);
}

////////////////////////////////////////////////////////////
void sortedStack::push(int data)
{
        // is full, not possible to push a new element
        if (isFull())
        {
                cout << " stack overflow!" << endl;
                return;
        }
        // if the stack is empty or the new element is smaller 
        //  than the top value just do simple push
        int top_data = peek();
        if ((data >= top_data) | (isEmpty()))
        {
                _mainStack[++_top] = data;
                return;
        }

        // otherwise, use aux-stack to push the new element in the right place
        while(~isEmpty() & (top_data > data ))
        {
                _auxStack[++_aux_top] = top_data;
                pop();
                top_data = peek();
        }
        _mainStack[++_top] = data;
        // re-push the lements in aux-stack back to the main stack
        while(_aux_top >= 0)
        {
                _mainStack[++_top] = _auxStack[_aux_top--];         
        }
        return;
}

////////////////////////////////////////////////////////////
void sortedStack::pop()
{
        if (isEmpty())
        {
                cout << " stack unerflow!" << endl;
                return;
        }
        _top--;
}

////////////////////////////////////////////////////////////
int sortedStack::peek()
{
        if (isEmpty())
        {
                cout << " stack is empty!" << endl;
                return INT_MAX;
        }
        return _mainStack[_top];
}

void sortedStack::print()
{
        if (isEmpty())
        {
                cout << " stack is empty!" << endl;
                return;
        }
        cout << " the elemets of stack " << endl;
        for (int i=0; i<=_top; i++)
                cout << _mainStack[i] << " " ;
        cout << endl; 
}

////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////

int _tmain(int argc, _TCHAR* argv[])
{
        sortedStack myStack(10);
        myStack.push(1);
        myStack.push(15);
        myStack.push(32);
        myStack.push(4);
        myStack.push(1);
        myStack.print();        
        myStack.pop();
        myStack.pop();
        myStack.push(77);
        myStack.push(10);
        myStack.pop();
        myStack.push(-15);   
        myStack.print();        
        return 0;
}

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/******************************************************************************************
*******************************************************************************************
Chapter 3 Stack and Queue

Implement a MyQueue class which implements a queue using two stacks.
We use two stacks, s1 and s2 for enqueue and dequeue. 
 
By: Hamed Kiani (Sep. 7, 2015)
******************************************************************************************
******************************************************************************************/

#include "stdafx.h"
#include <iostream>
using namespace std;

struct Node{
        int data;
        Node *next;
};

class MyQueue{
private:
        Node *_s1_head;     // enQueue is done using s1
        Node *_s2_head;     // s2 is used for dequeue
        int _s1_size;    // the size of s1 stack    
        int _s2_size;    // the size of s2 stack
        
public:
        MyQueue();
        ~MyQueue();
        void enQueue(int data);    // enqueue data value using s1
        Node* deQueue();             // dequeue using s1 and s2
        void print_s1();          // print elements of s1 stack
        void print_s2();          // print elements of s2 stack
        bool isEmpty(Node *); // check if s1 or s2 are empty
        int get_s1_size(){return _s1_size;}        // return size of s1
        int get_s2_size(){return _s2_size;}        // return size of s2
};

////////////////////////////////////////////////////////////////////
MyQueue::MyQueue()
{
        _s1_head = NULL;
        _s2_head = NULL; 
        _s1_size = 0;
        _s2_size = 0;
        cout << "the stack and queue are initialized! " << endl;
}

////////////////////////////////////////////////////////////////////
MyQueue::~MyQueue()
{
        Node *temp;
        
        while(_s1_head != NULL)
        {
                temp = _s1_head;
                _s1_head = _s1_head->next;
                delete temp;
        }

        while(_s2_head != NULL)
        {
                temp = _s2_head;            
                _s2_head = _s2_head->next;
                delete temp;
        }
        cout << "the stack and queue are deleted! " << endl;
}

////////////////////////////////////////////////////////////////////
// enQueue data at begin of s1 (push s1 stack)
void MyQueue::enQueue(int data)
{
        Node *temp = new Node;
        temp->data = data;
        temp->next = _s1_head;
        _s1_head = temp;
        _s1_size++;  
        cout << " the enQueue value is: " << data << endl;
}

////////////////////////////////////////////////////////////////////
// For deQueue, 
// we copy all from s1 to ss except the last node of s1 O(n)
// re-copy s2 to s1 in reverse order O(n)
// update the s1_size and s2_size
Node* MyQueue::deQueue()
{
        // the queue is empty and dequeue is not possible
        if ((_s1_size == 0) )
        {
                cout<< "dequeue is not possible !" << endl;
                return NULL;                 
        }

        // there is just one element in queue
        if ((_s1_size == 1) )
        {
                Node * temp = _s1_head;
                _s1_head = NULL;
                _s1_size--;
                cout << " the dequeue value is: " << temp->data << endl;
                return temp;
        }

        // there are more than one element in the queue
        _s2_head = _s1_head;
        _s1_head = NULL;
        Node * temp;
        temp = _s2_head;
        _s1_size--;
        while(temp->next->next != NULL)
        {
                temp = temp->next;
        }
        Node * temp2;
        temp2 = temp->next;
        temp->next = NULL;       
        _s1_head = _s2_head;
        _s2_head = NULL;
        cout << " the dequeue value is: " << temp2->data << endl;
        return temp2;
}

////////////////////////////////////////////////////////////////////
void MyQueue::print_s1()
{
        if (_s1_head == NULL)
        {
                cout << " stack s1 is empty" << endl;
                return;
        }
        Node* temp;
        temp = _s1_head;
        while(temp)
        {
                cout << temp->data << " " ;
                temp = temp->next;
        }
        cout << endl;
}

//////////////////////////////////////////////////////////
void MyQueue::print_s2()
{
        if (_s2_head == NULL)
        {
                cout << " stack s2 is empty" << endl;
                return;
        }
        Node* temp;
        temp = _s2_head;
        while(temp)
        {
                cout << temp->data << " " ;
                temp = temp->next;
        }
        cout << endl;
}
////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////

int _tmain(int argc, _TCHAR* argv[])
{
        MyQueue queue;
        queue.enQueue(1);        
        cout << queue.get_s1_size() << endl;
        cout << queue.get_s2_size() << endl;
        queue.print_s1();
        queue.print_s2();
        Node * temp = queue.deQueue();
        temp = queue.deQueue();
        temp = queue.deQueue();
        temp = queue.deQueue();
        temp = queue.deQueue();
        queue.print_s1();
        queue.print_s2();
        queue.enQueue(3);
        queue.enQueue(4);
        queue.print_s1();
        queue.print_s2();
        return 0;
}

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/******************************************************************************************
*******************************************************************************************
Chapter 3 Stack and Queue

Imagine a (literal) stack of plates.
If the stack gets too high, it might topple.
Therefore, in real life, we would likely start a new stack when the previous stack exceeds some threshold. 
Implement a data structure SetOfStacks that mimics this.
Implement a function popAt(int index) which performs a pop operation on a specific sub-stack.
 
By: Hamed Kiani (Sep. 7, 2015)
******************************************************************************************
******************************************************************************************/

#include "stdafx.h"
#include <iostream>
using namespace std;

class SetOfStacks{
private:
        int _numOfStk;   // number of stacks
        int _thOfStk;    // threshold of stacks
        int _curStk;     // index of current stack
        int **_stacks;       // two-dim array to keep stacks elements
        int *_elmts; // number of elements in each stack

public:
        SetOfStacks(int n, int t);
        ~SetOfStacks();
        void push(int n);  // push the element n on the stack
        int pop();                        // pop operation
        int pop(int k);            // pop operation from stack k
        bool isFull(int k);        // is stack k full?
        bool isFull();            // is the stack full?
        bool isEmpty(int k);//        is the stack k empty?
        bool isEmpty();           // is the stack empty?
        void printAll();  // print all elements
        void printK(int k);        // print elemets of stack k
};

////////////////////////////////////////////////////////////       
SetOfStacks::SetOfStacks(int n, int t)
{
        _numOfStk = n;
        _thOfStk  = t;
        _curStk   = 0;

        // _elmts = new int[_numOfStk];
        _elmts = (int*) malloc(_numOfStk * sizeof(int));
        for(int i = 0; i < _numOfStk; i++)
                _elmts[i] = -1;  // all are empty


        _stacks = (int **) malloc(_numOfStk * sizeof(int *));
        for (int i = 0; i<_numOfStk; i++)
                _stacks[i] = (int *) malloc(_thOfStk * sizeof(int));
        cout << n << " stacks are created, windex 0,..., " << n-1 << endl;
        cout << " the threshold for each stack is " << t << " elements " << endl;
}

////////////////////////////////////////////////////////////
SetOfStacks::~SetOfStacks()
{
        free(_elmts);
        free(_stacks);
        cout << " stacks are deleted!" << endl;
}

////////////////////////////////////////////////////////////
bool SetOfStacks::isFull(int k)
{
        return (_elmts[k] == _thOfStk-1);
}

////////////////////////////////////////////////////////////
bool SetOfStacks::isFull()
{
        return isFull(_numOfStk-1);
}

////////////////////////////////////////////////////////////
bool SetOfStacks::isEmpty(int k)
{
        return (_elmts[k] == -1);
}

////////////////////////////////////////////////////////////
bool SetOfStacks::isEmpty()
{
        return isEmpty(0);
}

////////////////////////////////////////////////////////////
void SetOfStacks::push(int n)
{
        if (isFull())
        {
                cout << "stack overflow! cann't push " << n << " value! " << endl;
                return;
        }       
        if (_elmts[_curStk] == _thOfStk - 1)
                _curStk++;
        cout << "value " << n << " pushed on stack " << _curStk <<  endl;
        _elmts[_curStk]++;
        _stacks[_curStk][_elmts[_curStk]] = n;
}

////////////////////////////////////////////////////////////
int SetOfStacks::pop()
{
        if (isEmpty())
        {
                cout << "stack under flow! " << endl;
                return INT_MAX;
        }
        int i = _stacks[_curStk][_elmts[_curStk]];
        cout << "value " << i << " is popped from stack " << _curStk << endl;
        _elmts[_curStk]--;  
        if ((_elmts[_curStk] == -1) & (_curStk > 0))
                _curStk--;
        
        return i;
}

////////////////////////////////////////////////////////////
int SetOfStacks::pop(int k)
{
        if (isEmpty(k))
        {
                cout << "stack under flow!" << endl;
                return INT_MAX;
        }

        if ((k > _numOfStk-1) | (k < 0))
        {
                cout << " stack index is out of range! " << endl;
                return INT_MAX;
        }

        
        int i = _stacks[k][_elmts[k]];
        cout << "value " << i << " is popped from stack " << k << endl;
        _elmts[k]--;
        if ((_elmts[k] == -1) & (k > 0) & (k == _curStk))
                _curStk--;
        return i;
}

////////////////////////////////////////////////////////////

void SetOfStacks::printAll()
{
        cout << "print all the stacks:" << endl;
        for (int i = 0; i < _numOfStk; i++)
        {
                if (isEmpty(i))
                        cout << "stack " << i <<  " is empty " << endl;
                else
                {
                        for (int j = 0; j <= _elmts[i]  ; j++)
                                cout << _stacks[i][j] << " " ;
                        cout << endl;
                }
        }
}

////////////////////////////////////////////////////////////
void SetOfStacks::printK(int k)
{
        if (k > _numOfStk-1)
        {
                cout << "index is more than the stack size!" << endl;
                return;
        }

        if (k < 0)
        {
                cout << "index is less than the stack size!" << endl;
                return;
        }

        if (isEmpty(k))
                        {
                                cout << "stack " << k <<  " is empty " << endl;
                                return;
        }
                else
                {
                        for (int j = 0; j <= _elmts[k]  ; j++)
                                cout << _stacks[k][j] << " " ;
                        cout << endl;
                }
}

////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////

int _tmain(int argc, _TCHAR* argv[])
{
        int n = 2;
        int t = 3;
        SetOfStacks stacks(n,t);
        
        stacks.push(1);
        stacks.push(2);
         stacks.push(3);
        
        stacks.push(10);
        stacks.push(20);
        stacks.push(30);

        stacks.push(100);
        stacks.push(200);
        stacks.push(300);

        stacks.push(1000);
        stacks.push(2000);
        stacks.push(3000);
        stacks.push(3001);
        stacks.push(3002);       

        stacks.printK(0);
        stacks.printK(1);
        stacks.printK(2);
        stacks.printK(3);
        stacks.printK(4);

        stacks.printAll();

        stacks.pop();
        stacks.pop();
        stacks.pop(0);
        stacks.pop(0);
        stacks.pop(0);
        stacks.pop(2);
        stacks.printAll();
        return 0;
}

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/******************************************************************************************
*******************************************************************************************
Chapter 3 Stack and Queue

Design a stack which, in addition to push and pop, also has a function min which returns the minimum element? 
Push, pop and min should all operate in O(1) time.
We design this class using array instead of linkedlist
 
By: Hamed Kiani (Sep. 2, 2015)
******************************************************************************************
******************************************************************************************/

#include "stdafx.h"
#include <iostream>
using namespace std;

class minStack{

private:
        int* _main_stk;      // main stack
        int* _aux_stk;       // aux. stack to keep elements in sorted
        int _cap;        // the maximum capacity of stack
        int _top;        // size of stack

public:
        minStack(int n);
        ~minStack();
        void push(int data);
        int pop();
        bool is_empty();
        bool is_full();
        void print_stk();
        void print_aux_stk();
        int getMin();
};

minStack::minStack(int n)
{
        _cap = n;
        _main_stk = new int[_cap];
        _aux_stk  = new int[_cap];
        _top = -1;       
        cout << " an object of minStack is created!" << endl;
}

minStack::~minStack()
{       
        delete[] _main_stk;
        delete[] _aux_stk;
        cout << " an object of minStack is deleted!" << endl;
}

bool minStack::is_empty()
{
        return (_top == -1);
}

bool minStack::is_full()
{
        return (_top == _cap-1);
}

void minStack::push(int data)
{
        if (is_full())
        {
                cout << "stack overflow!" << endl;
                return;
        }
        cout << " The element " << data << " is pushed on the stack!" << endl;
        // if the stack is empty or data is less than all elements in the aux. stack, just push it
        if ((_top == -1) || (data <= _aux_stk[_top]))
        {
                _top++;             
                _main_stk[_top] = data;
                _aux_stk[_top]  = data;             
                return;
        }

        // otherwise, push data on the main stack and duplicate the current min in the new position
        int temp = _aux_stk[_top];
        _top++;             
        _main_stk[_top] = data;     
        _aux_stk[_top] = temp;      
}

// pop operation: simply just _top--!
int minStack::pop()
{
        if (is_empty())
        {
                cout << "underflow!" << endl;
                return INT_MAX;
        }       
        _top--;
        cout << " The element " << _main_stk[_top+1] << " is popped from the stack!" << endl;
}

// return min value
int minStack::getMin()
{
        return _aux_stk[_top];
}

// print the main stack
void minStack::print_stk()
{
        if (is_empty())
        {
                cout << " nothing to print!" << endl;
                return;
        }
        for (int j = 0; j <= _top; j++)
                cout << _main_stk[j] << " " ;
        cout << endl;
}

// print the main stack
void minStack::print_aux_stk()
{
        if (is_empty())
        {
                cout << " nothing to print!" << endl;
                return;
        }
        for (int j = 0; j <= _top; j++)
                cout << _aux_stk[j] << " " ;
        cout << endl;
}

////////////////////////////////////////////////////////////

int _tmain(int argc, _TCHAR* argv[])
{
        minStack stack(10);

        stack.push(12);
        stack.push(3);
        stack.push(4);   
        stack.push(11);

        stack.push(12);
        cout << "the min value is : " << stack.getMin() << endl;
        stack.push(11);
        stack.push(41);
        cout << "the min value is : " << stack.getMin() << endl;
        stack.push(12);
        stack.push(1);
        stack.push(3);
        
        cout << "the min value is : " << stack.getMin() << endl;
        stack.print_stk();
        stack.print_aux_stk();

        cout << "the min value is : " << stack.getMin() << endl;
        stack.pop();
        stack.pop();
        stack.pop();
        cout << "the min value is : " << stack.getMin() << endl;
        stack.print_stk();
        stack.print_aux_stk();
        return 0;
}

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/******************************************************************************************
*******************************************************************************************
Chapter 3 Stack and Queue

A class of K Stacks in a single array! Efficient memory and run time. 
 
By: Hamed Kiani (Sep. 2, 2015)
******************************************************************************************
******************************************************************************************/

#include "stdafx.h"
#include <iostream>
using namespace std;

class kStacks{

private:
        int *arr;    // an array of size n to save the values in stacks
        int *top;    // an array of size k to keep the index of top values of k stacks
        int *next;   // an array of size n to keep the next entry in stacks
        int n,k; // n: size of array, k: number of stacks
        int next_slot;   // the next free slot in the array 

public:
        kStacks(int k1, int n1);
        ~kStacks();         
        bool is_full() { return (next_slot == -1);}
        bool is_empty(int sn) { return(top[sn] == -1);}
        void push(int sn, int data);
        int pop(int sn);
        void print_sn(int sn);
};

// constructor
kStacks::kStacks(int k1, int n1)
{
        k = k1; n = n1; 
        arr  = new int[n];    // to keep the values in the stacks
        top  = new int[k];    // to keep the last index of stacks
        next = new int[n];    // to handle the next and previous index of stacks

        // initial to -1, all k stacks are empty
        for (int i = 0; i < k; i++)
                top[i] = -1;

        // the next slot of each entry is the next index
        for (int i = 0; i < n-1; i++)
                next[i] = i+1;

        // for the last entry there is no free slot
        next[n-1] = -1;
        // the initial free slot is arr[0]
        next_slot = 0;
}

// destructor
kStacks::~kStacks()
{
        k = 0; n = 0;
        delete[] arr;
        delete[] next; 
        delete[] top;
}
 
// push operator
void kStacks::push(int sn, int data)
{
        // wrong stack number
        if (sn > k-1)
        {
                cout << "sn must be in [0...k-1]" << endl;
                return;
        }

        // first check if the stack sn is overflow
        if (is_full())
        {
                cout << "stack overflow! cann't push!" << endl;
                return;
        }
        // keep the next free slot in i, we will use this to push data in arr
        int i = next_slot;
        // update the next free slot using next[i]. next free slot will be used for next push operation
        next_slot = next[i];
        // now we use next in a different role, to keep the second top value in stack, 
        next[i] = top[sn];
        // update the top by i
        top[sn] = i;
        // push the data in arr[i]
        arr[i] = data;
}

// pop operator
int kStacks::pop(int sn)
{
        if (sn > k-1)
        {
                cout << "sn must be in [0...k-1]" << endl;
                return INT_MAX;
        }
        if (is_empty(sn))
        {
                cout << "stack underflow! cann't pup!" << endl;
                return INT_MAX;
        }
        // keep the current index of stack sn
        int i = top[sn];
        // keep the previous index of stack sn in top
        top[sn] = next[i];
        // initialize the next[i] by next free slot
        next[i] = next_slot;
        // next free slot is current i
        next_slot = i;
        // return current value
        return arr[i];
}

// print the stack sn
void kStacks::print_sn(int sn)
{
        if (sn > k-1)
        {
                cout << "sn must be in [0...k-1]" << endl;
                return;
        }
        if (is_empty(sn))
        {
                cout << "no value to print" << endl;
                return;
        }

        int i = top[sn];
        
        while(next[i] != -1)
        {
                cout << arr[i] << " ";
                i =  next[i];
        }
        // for the last stack value with next[i] = -1;
        cout << arr[i] << endl;
}


int _tmain(int argc, _TCHAR* argv[])
{
        kStacks stack(3, 10);
        stack.push(0, 1);
        stack.push(0, 2);
        stack.push(0, 3);

        stack.push(1, 10);
        stack.push(1, 20);

        stack.push(2, 100);
        stack.push(2, 200);

        stack.print_sn(0);

        stack.pop(0);
        stack.pop(0);
        stack.print_sn(0);
        
        stack.print_sn(1);
        stack.print_sn(2);
        return 0;
}

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/******************************************************************************************
*******************************************************************************************
Chapter 3 Stack and Queue

A simple class of Stack!
 
By: Hamed Kiani (Sep. 1, 2015)
******************************************************************************************
******************************************************************************************/

#include "stdafx.h"
#include <iostream>
using namespace std;


struct Node{
        int _data;
        Node* _next;
};

class myStack{
private:
        Node* _head;
        int _size;

public:
        myStack();
        ~myStack(); 
        void push(int data);
        void pop();
        Node* return_top();
        int get_size();
        bool is_empty();
        void clear();
        void print_stack();
};

// constructor
myStack::myStack()
{
        _head = NULL;
        _size = 0;
}
myStack::~myStack()
{
        clear();
}

// is empty function
bool myStack::is_empty()
{
        return (_size == 0);
}

// retrun the stack size
int myStack::get_size()
{
        return _size;
}

// puch on the top
void myStack::push(int data)
{
        Node* temp = new Node;
        temp->_data = data;
        temp->_next = _head;
        _head = temp;
        _size++;
}

// pop the top data
void myStack::pop()
{
        if (is_empty())
        {
                cout << " the stack is empty, poping faild" << endl;
                return;
        }

        Node* temp  = _head;
        _head = _head->_next;
        delete temp;
        _size--;
}

// return the pointer of the top value
Node* myStack::return_top()
{
        if (is_empty())
                return NULL;
        Node* temp = _head;
        return temp;
}

// empty the stack
void myStack::clear()
{
        while(_size)
                pop();
        cout << " stack is deleted" << endl;
}

// print the stack values
void myStack::print_stack()
{
        Node* temp = _head;
        while(temp != NULL){
                cout << temp->_data << " " ;
                temp = temp->_next;
        }
        cout << endl;
}


int _tmain(int argc, _TCHAR* argv[])
{
        myStack stack;  
        stack.push(1);
        stack.push(2);
        stack.push(3);
        stack.print_stack();
        cout << stack.get_size() << endl;
        stack.pop();
        stack.print_stack();

        Node* temp = stack.return_top();
        cout << temp->_data << endl;

        return 0;
}